On the Component Parts of Iron-flows. 255 



with a fmall proportion of (ilex. Its inflammability is great, 

 and it requires a cautious preparation for the blad-fumace. 

 For this purpofe it is built upon a thin layer of coals, in 

 piles not exceeding 20 inches, or 2 feet : the coals are kin- 

 dled in the ufual manner, and convey ignition to the incum- 

 bent (tone. Thefe precautions are absolutely neceffary, other- 

 wife the whole ftone would be connected in one general mafs 

 by fufion. 



f expofed of this ftone to diftillation - - 979 grs, 

 in a bright red heat for 7 hours, during which time 

 a confidcrable degree of combuftion took place, 

 and a black vapour was difengaged ; when cool, 

 the refidue weighed - 475 



Loft, of water, bitumen, and carbon, equal to 

 5 ! A per cent. - - - - 503 grs. 



In this (late, the iron-ftone was divided into thin, blue 

 laminae, of a vitreous nature, and very weakly magnetic. 



I next torrefied, of this' (lone in contact with charcoal- 

 dud, - - 1 163 grs. 



When feparated, wafhed, and dried, the refi- 

 due weighed - 590 



Lofs of mixtures equal to 49 + - per cent. - 573 grs. 



The charcoal was in part confumed,, and part of the fur- 

 face of the ore expofed to contact with air, otherwife it is 

 probable that the lofs in de-oxygenation would have been 

 lefs, by the quantity of carbon contained in the (lone, than 

 in torrefying in the open air ; where the carbon mull infallibly 

 be confumed, and the lofs greater. In this (late of de-oxy- 

 genation this iron-done pufferies the ufual properties peculiar 

 to the other varieties. At Clough it is highly cdeemed, 

 both as to the quantity and quality of the iron it affords. 

 It is reckoned, in a torrefied date, to yield in the blalt-furnace 

 from 55 to 60 per cent. This is eafily accounted for, when 

 it is coufidered, that it lofes more than half its weight in 

 torrefaction. 



y IV. A 



